Over the past decade and a half, Greenland has shown a powerful trend toward increased melt. The image above, provided by Marco Tedesco, who recently released a report on 2012’s record Greenland melt, shows a stark trend of increased melt ending in the unprecedented melt season that occurred this year.

Note that the above graph only shows cumulative melt through August 8th of this year, so final melt index values are likely to be even higher.

“The melting index is computed from passive microwave satellite measurements and it can be seen as a measure of the ‘strength’ of the melting season: the higher the index the more melting occurred. With more melting yet to come during August, 2012 will position itself way above the old records, likely becoming the ‘Goliath’ of the melting years during the satellite record (1979 – to date).”

Overall, seasonal melt has been far above the average range with many areas experiencing melt for 50 days longer than the average season:

(Image credit: Marco Tedesco)

Cumulative mass loss is also running higher than previous record years with 2012 at 90 gigatons of mass lost through the end of July. The last record year, 2010 showed 60 gigatons of mass lost through the same period. August tends to show high mass loss rates and mass loss can continue through September, so we will have to wait for final values in these figures.

Other indicators of the resiliency of the Greenland Ice Sheet are also coming in. Jason Box tracks Greenland’s reflectivity (albedo) and has made some startling observations. You can see from the image below that the reflectivity of Greenland’s ice sheet has been far lower than any previous year in the record:

(Image credit: Jason Box)

Based on secondary observations, Jason has speculated that this is possibly the lowest reflectivity for Greenland since the Medieval Warm Period which peaked in 1150.

Reflectivity is important because it determines how much solar radiation the ice sheet absorbs. The more radiation absorbed, the greater the potential for melt.

In all, this has been a critical year for Greenland, and should ice melt trends continue within this range or increase, it will become increasingly clear that Greenland is encountering a melt tipping point.